How to Calculate German Water Hazard Class (WGK) for Substances and Mixtures

Little Pro on 2016-01-08

German Water Hazard Class (WGK) sometimes is also called German Water Endangerment Class (WGK). This is often included in the section 15 of SDSs. German's Federal Water Act requires that facilities handling substances that are hazardous to waters must be built and operated in a way that water bodies are protected from pollutions. To this end, the Water Hazard Class (WGK) of a substance or mixture has to be determined, communicated and documented.

Classification is carried out on the basis of the Ordinance on facilities for handling substances that are hazardous to water (Verordnung über Anlagen zum Umgang mit wassergefährdenden Stoffen (AwSV)) of 18 April 2017. There are three water hazard classes (WGK). 

• 1: low hazard to waters;
• 2: hazard to waters;
• 3: severe hazard to waters;

Furthermore, substances can be classified as non-hazardous to water (nwg) or are deemed hazardous to water in general (awg).

In this article, we will show you how to determine the Water Hazard Class (WGK) for substances and mixtures and how to document them in a compliant way. 

How to Determine German Water Hazard Class (WGK) for Substances

For substances, you can search for published WGK classifications directly on UBA's website below. You can search a substance by name, CAS number or EC number.

• https://webrigoletto.uba.de/rigoletto/public/searchRequest.do?event=request

Substances that are currently not published with a WGK classification in the Bundesanzeiger or on UBA's website are regarded as not classified and must be regarded as highly hazardous to water (WGK 3) for reasons of precaution. Facility operators are obliged to self-classify these substances according to Annex 1 of AwSV and to submit the WGK documentation to the Umweltbundesamt (UBA).

When you prepare WGK self-classification for an unlisted substance, you must know its GHS hazard statements and what data is available. They are used to calculate total evaluation points. The WGK will then be determined based on total points.

• Total evalulation points (TEP) = Ealulation points based on hazards + Precautionary points
• TEP (0~4): WGK 1
• TEP (4-8): WGK 2
• TEP (>8): WGK 3

Part 1: Evalulation Points Based on Hazard Statements

Part 2 Precautionary Points

• No information concerning acute oral and dermal toxicity: 4 points
• No information concerning effects on the environment: 8 points. The number of precautionary points is reduced by two if proof is furnished that the substance is easily biodegradable and the potential for bioaccumulation has been ruled out.
•  If no risk phrases or hazard statements on effects on the environment are assigned to a substance and there are known tests on the substance’s effects on the environment, the following precautionary points shall be assigned:
• a) 8 precautionary points if a test is known according to which acute toxicity in a species of fish (96 h LC₅₀), or species of water flea (48 h LC₅₀), or the inhibition of algae growth (72 h IC₅₀) is not more than 1 mg/l and

aa) there is no proof that the substance is easily biodegradable or

bb) there is no proof to rule out the potential for bioaccumulation,

b) 6 precautionary points if a test is known according to which acute toxicity in a species of fish (96 h LC₅₀), or species of water flea (48 h LC₅₀), or the inhibition of algae growth (72 h IC₅₀) is more than 1 mg/l but not more than 10 mg/l and

aa) there is no proof that the substance is easily biodegradable or

bb) there is no proof to rule out the potential for bioaccumulation,

c) 4 precautionary points if a test is known according to which acute toxicity in a species of fish (96 h LC₅₀), or species of water flea (48 h LC₅₀), or the inhibition of algae growth (72 h IC₅₀) is more than 10 mg/l but not more than 100 mg/l and there is no proof that the substance is easily biodegradable in bodies of water,

d) 2 precautionary points if only tests are known according to which acute toxicity in a species of fish (96 h LC₅₀), or species of water flea (48 h LC₅₀), or the inhibition of algae growth (72 h IC₅₀) exceeds 100 mg/l and

aa) there is no proof that the substance is easily biodegradable in bodies of water, and

bb) there is no proof to rule out the potential for bioaccumulation.

Determination of Water Hazard Class (WGK) for Mixture

All mixtures have to be self-classified. WGK classifications of mixtures are not submitted to the Umweltbundesamt. These classifications have to be documented according to Appendix 2 Number 2 or 3 of the AwSV and have to be made available to the local authorities on request. 

The WGK of a mixture should be determined either by using a calculating rule and the WGK of each component of the mixture or on the basis of experimental test data generated with the mixture.

To determine the WGK for a mixture, you need to obtain its composition info and determine the WGK for each component first. Then the mass fractions of the individual components are added up by their WGK, and the WGK of the mixture is then determined according to the table below.

Components are taken into account if their fraction exceeds the following thresholds:

• 0.1% in the case of carcinogenic substances
• 0.2% in the case of all other substances;
• If carcinogenic substances are actively added to a mixture and their fraction is less than 0.1%, the mixture is classified at least into WGK 1;
• the same applies when the fraction of WGK 3 additives is less than 0.2%.

Important: If it is necessary to factor in an M factor in the case of a WHC 2 or WHC 3 substance on account of its high aquatic toxicity, the percentage of the substance in question is multiplied by this factor. 

Classification of Substances and Mixtures as Non-Hazarous

2.1 Substances

Substances are deemed to be non-hazardous to water if they meet all of the requirements mentioned below:

a) The sum of evalulation points is zero.

b) A liquid substance possesses a water solubility of less than 10 mg/l.

c) A solid substance possesses a water solubility of less than 100 mg/l.

d) There is no known test according to which the acute toxicity in a species of fish (96 h LC₅₀) or species of water flea (48 h EC₅₀) or the inhibition of algae growth (72 h IC₅₀) is below the limit of solubility. Valid tests must have been conducted on two of the aforementioned organisms,

e) A liquid organic substance is easily biodegradable.

f) A solid organic substance is either easily biodegradable or does not have an increased bioaccumulation potential.

g) A substance which is hazardous to water does not originate as a result of easy biodegradability or abiotic degradability.

h) The substance is not a floating liquid substance pursuant to point 1.3.

2.2 Mixtures

Mixtures are deemed to be non-hazardous to water if they meet all of the requirements mentioned below:

a) The content of WHC 1 substances is less than 3 % by mass.

b) The content of WHC 2 substances is less than 0.2 % by mass.

c) The content of WHC 3 substances is less than 0.2 % by mass.

d) The content of unidentified substances is less than 0.2 % by mass.

e) No carcinogenic substances as per point 1.2 were purposefully added to the mixture.

f) No substances under WHC 3 were purposefully added to the mixture.

g) No substances with unknown water hazard properties were purposefully added to the mixture.

h) No dispersants or emulsifiers were purposefully added to the mixture.

i) The mixture does not float in bodies of water situated aboveground.

Note: Floating liquid substances are deemed to be generally hazardous to water.

References

• Introduction to German Water Hazard Class - by UBA
• Overview of AsSV
• AwSV - English Draft

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 Tags: Topics - GHS, GHS Basics and Tutorials